Apparatus are known for use in connection with the middle and inner ear where the apparatus is capable of (1) delivering various liquids and solids to the inner ear structures; (2) extracting, withdrawing, or exchanging fluid materials from the inner ear; (3) transferring fluid materials into and out of the inner ear via the round window membrane so that items [1] and [2] can be accomplished; (4) enabling middle and inner ear structures to be electrophysiologically monitored using electrocochleography (“ECoG”) procedures; (5) altering the permeability of the round window membrane in the ear for a variety of therapeutic purposes with drugs, chemical agents, or iontophoresis; and (6) creating a discrete sealed or non-sealed “fluid-receiving zone” within the round window niche so that fluid materials can be transferred into and out of the inner ear via the adjacent round window membrane in a controlled and site-specific manner.
In order to treat ear disorders, it has been necessary to deliver therapeutic agents to various ear tissues in a controlled, safe, and efficient manner. For example, a variety of structures have been developed which are capable of delivering/administering therapeutic agents into the external auditory canal of the outer ear. U.S. Pat. No. 4,034,759 to Haerr discloses a hollow, cylindrical tube manufactured of sponge material (e.g. dehydrated cellulose) which is inserted into the external auditory canal of a patient. When liquid medicines are placed in contact with the tube, it correspondingly expands against the walls of the auditory canal. As a result, accidental removal of the tube is prevented. Furthermore, medicine materials absorbed by the tube are maintained in contact with the walls of the external auditory canal for treatment purposes. Other absorbent devices designed for treatment of the external auditory canal and related tissue structures are disclosed in U.S. Pat. No. 3,528,419 to Joechle, U.S. Pat. No. 4,159,719 to Haerr, and U.S. Pat. No. 2,642,065 Negri. The Negri patent specifically describes a medicine delivery device with an internally-mounted, frangible medicine container which, when broken, releases liquid medicines into an absorbent member.
However, the delivery of therapeutic agents in a controlled and effective manner is considerably more difficult with respect to tissue structures of the inner ear (e.g. those portions of the ear surrounded by the otic capsule bone and contained within the temporal bone which is the most dense bone tissue in the entire human body). The same situation exists in connection with tissue materials which lead into the inner ear (e.g. the round window membrane). Exemplary inner ear tissue structures of primary importance for treatment purposes include but are not limited to the cochlea, the endolymphatic sac/duct, the vestibular labyrinth, and all of the compartments (and connecting tubes) which include these components. Access to the above-described inner ear tissue regions is typically achieved through a variety of structures, including but not limited to the round window membrane, the oval window/stapes footplate, the annular ligament, the otic capsule/temporal bone, and the endolymphatic sac/endolymphatic duct, all of which shall be considered “middle-inner ear interface tissue structures” as described in greater detail below. In addition, as indicated herein, the middle ear or tympanic cavity shall be defined as the physiological air-containing tissue zone behind the tympanic membrane (e.g. the ear drum) and proximal to the inner ear.
The inner ear tissues listed above are of minimal size and only readily accessible through microsurgical procedures. In order to treat various diseases and conditions associated with inner ear tissue˜ the delivery of medicines to such structures is often of primary importance. Representative medicines which are typically used to treat inner ear conditions include but are not limited to urea, mannitol, sorbitol, glycerol, lidocaine, xylocaine, epinephrine, immunoglobulins, sodium chloride, steroids, heparin, hyaluronidase, aminoglycoside antibiotics (streptomycin/gentamycin), antioxidants, neurotrophins, nerve growth factors, various therapeutic peptides, and polysaccharides. Of particular interest in this list are compounds which are used to alter the permeability of the round window membrane within the ear using, for example, hyaluronidase and iontophoretic techniques (defined below). Likewise, treatment of inner ear tissues and/or fluid cavities may involve altering the pressure, volume, electrical activity, and temperature characteristics thereof. Specifically, a precise balance must be maintained with respect to the pressure of various fluids within the inner ear and its associated compartments. Imbalances in the pressure and volume levels of such fluids can cause various problems, including but not limited to conditions known as endolymphatic hypertension, perilymphatic hypertension, perilymphatic fistula, intracochlear fistula, Meniere's disease, tinnitus, vertigo, hearing loss related to hair cell or ganglion cell damage/malfunction, and ruptures in various membrane structures within the ear.
Of further interest regarding the delivery of therapeutic agents to the middle ear, inner ear, and middle-inner ear interface tissue structures are a series of related and co-owned patents, namely, U.S. Pat. Nos. 5,421,818; 5,474,529, and 5,476,446 all to Arenberg. Each of these patents discloses a medical treatment apparatus designed to deliver fluid materials to internal ear structures. U.S. Pat. No. 5,421,818 describes a treatment system which includes a tubular stem attached to a reservoir portion with an internal cavity designed to retain a supply of therapeutic fluid compositions therein. The side wall of the reservoir portion further comprises fluid transfer means (e.g. pores or a semi-permeable membrane). Contact between the fluid transfer means and the round window membrane in a patient allows fluid materials to be delivered on-demand to the round window membrane, followed by diffusion of the fluid materials through the membrane into the inner ear. U.S. Pat. No. 5,474,529 involves a therapeutic treatment apparatus with a plurality of reservoir portions (e.g. a first and a second reservoir portion in a preferred embodiment) which are connected to multiple tubular stems that are designed for implantation into the endolymphatic sac and duct using standard microsurgical techniques. Finally, U.S. Pat. No. 5,476,446 discloses a therapeutic treatment apparatus which includes a reservoir portion for retaining liquid medicine materials therein, a first tubular stem on one side of the reservoir portion, and a second tubular stem on the opposite side of the reservoir portion. The second stem is designed to reside within the external auditory canal of a patient lateral to the ear drum, while the first stem is sired for placement within an opening formed in the stapes footplate/annular ligament so that medicine materials in fluid form can be delivered into the inner ear from the reservoir portion (which resides in the middle ear cavity medial to the ear drum).
A different approach for transferring materials into and out of the inner ear via the round window membrane/round window niche is disclosed in U.S. patent application Ser. No. 08/874,208 filed on Jun. 13, 1997. This application describes a system in which one or more fluid transfer conduits are provided which are operatively connected to a “cover member” that is designed for placement on top of the niche (e.g. at its point of entry) or within the niche. The cover member is used to create a “fluid-receiving zone” (or “inner ear fluid transfer space”) which is partially or entirely sealed in order to facilitate fluid transfer into and out of the inner ear. In one embodiment, the cover member consists of a thin, solid, plate-like structure that is secured in position on top of the niche at its point of entry as previously noted. Alternatively, the cover member may comprise a portion of flexible and compressible material which, during placement within the round window niche, is compressed and thereafter allowed to expand once the portion of compressible material is positioned within the niche. As a result, the cover member can engage the internal side wall of the round window niche, thereby creating the fluid-receiving zone (“inner ear fluid transfer space”) between the compressible cover member and the round window niche. Representative materials used to construct the portion of compressible material associated with the cover member in this particular embodiment optimally involve foam-type products including but not limited to polyethylene foam, polyether foam, polyester foam, polyvinyl chloride foam, polyurethane foam, and sponge rubber (e.g. synthetic or natural), all of which are of the closed cell variety, with such materials being non-fluid-absorbent in accordance with the substantial lack of open cells therein. Specifically, the non-fluid-absorbent character of these materials results from the closed cell structure thereof which prevents fluid materials from being absorbed compared with open cell (absorbent) foam products.
The present invention represents an advance in the art of middle ear or tympanic cavity treatment, diagnosis, and medicine delivery as described in detail below. In part, the prior art treatment of acute middle ear infections has been based on tympanocentisis or insertion of tubes into the tympanum or tapping the ear with a conventional syringe or a aspirator. Aspirators are known which are adapted to apply suction using a vacuum which is based on an externally provided vacuum source or a vacuum that is generated by the withdrawal of a piston in the aspirator device. Generally, the use of surgical intervention has been accompanied with the evacuation of fluid in conjunction with the systemic administration of antimicrobial medicaments to treat the localized infection in the ear.
The present invention is concerned with providing a novel apparatus and method of treating middle ear infections that is capable of rapidly (a) making a surgical incision in the tympanum; (b) aspirating fluid from the behind the tympanum and (c) administering a dose of an antimicrobial compound using a compact handheld apparatus.